Clustering time series is often an important task performed in time series data mining applications. Typically, a historical data set is used, either directly or indirectly, as the source of clustering operations. That is, clustering techniques typically focus on the similarity patterns of time series data that has already been observed. It may be desirable, however, to provide time series clustering for a specific time or period of time in the future based on forecast data, instead of clustering based on observed data over time.